Safety lock for air hammers



June 29 1926. 1,590,442

A.QUA|TE SAFETY LOCK FOR AIR HAMMERS Filed oct. 2e, 1925 Patented June 23, 18.25.

UNITED STATES lijf-,93,442

PATENT OFFICE.

ANDREW QUAITE, OF CHICAGO, ILLNOIS, ASSIGNOR TO PULLMAN CAR AND MANU- FACTURING CORFOR-ATION, OF CHICAGO, ILLINOIS, A COREOBATON OF ILLINOIS.

SAFETY LOCK FOR AIR HAMMEES.

Application filed October 26, 1925. Serial No. 64,911.

The invention relates to mechanism for use on air hammers designed to lock the trigger controlling the air supply to prevent the accidental or premature admission of air to the hammer.

The principal object of my invention is to provide a lock mounted in the handle of ther hammer and movable to engage or release the trigger. l

A further object is to provide a lock in the handle of the hammer in position to be easily manipulated by the operator and so mounted that its presence in the handle will not interfere with the grip of the operator upon the handle of the hammer.

The foregoing and other objects are attained by the mechanism illustrated in the accompanying drawing in which Fig. l is a side elevational view of the handle of an air hammer equipped with the invention, Vwith portions of the handle broken away to better show the application of the lock;

Fig. 2 is an end elevational view of the handle;

Fig. 3 is an enlarged horizontal sectional view through handle and lock taken-on line 3-3 of Fig.` 1 looking in the direction inv dicated by the arrows and showing the lock stop mechanism; and

Fig. 4 is a horizontal sectional view taken on line 4 4 of Fig. 1 showing the relative positions of lock and throttle valve mechanisms.

In said drawing, indicates a handle of an air hammer secured to the usual hammer piston cylinder 11. The handle contains a throttle valve 12 mounted in the tube casing 13 fitted into the underside of the handle. The throttle valve 12 is seated upon .and supported by spring 14 held within the tube by vent plug 15 let into the lower end of the tube. The tube is perforated to provide air lports 16 and 17 communicating, respectively, with the piston cylinder 11 and nozzle 18 leading to the source of air supply. The usual reducing bushing 19 let into the nozzle 18 provides the necessary union between air line and hammer.

Above and to one side of the throttle valve tube casing 13 the handle 10 is provided with a slot 2O in which is accommodated a pivotally mounted control trigger 21 in position to engage the upper side of throttle valve 12. The trigger is eccentrically mounted with its pivot 22 positioned at one sidelof the throttle valve'12 and pro-' pivot 22 the trigger is provided with a projecting heel portion 24 adapted to ride upon throttle valve 12. Ther trigger is also Yshaped to provide a depending toe piece 25 below its pivot point 22 and positioned substantially at right angles to heel portion 24 for a purpose to be hereinafter described.

The side walls 26 of slot 2O are undercut or grooved as indicated at 27 in Figs. 1, 3 and 4 of the drawing along lines substantially parallel to throttle valve casing 13. Slidablymounted in said grooves is a T-sliaped lock 28 arranged with its central leg portion 29 projecting outwardly between side walls 26 of the slot and slightly beyond the adjacent surface of the handle. The projecting leg portion 29 is shaped to the contour of the handle at that point and is striated or serrated along its protruding edge as at 30 to insure operative engagement betweenk the lock and the lhand of the operator. j

Lock 28 is adapted to be moved upwardly to engage toe piece 25 of the trigger thereby locking the trigger, and downwardly from the trigger locking position indicated vin Figs. 1 and 2, to release the trigger. The lock is held-in its trigger engaging and released positions by means of a resilient lock retaining mechanism housed in one of the vlock grooves 27 at one side of the lock 28. vOn the side adjacent said mechanism the lock is provided with a pair of ball sockets '31l spaced apart a distance corresponding to the desired movement of the lock. These sockets 31 are designed to alternately receive a retaining ball 32 held against the lock by pressure of spring 33 confined in pocket 34 by adjustable plug 35 let into the pocket as best shown in Fig. 3. The retaining mechanism is held in position by the lock 28 and exerts only such pressure against the lock as may be required to hold the lock against displacement during hammering operations and permit the shifting thereof by the hand of the operator. The desired spring pressure may be obtained by manipulation of plug 35 by means of which the pressure upon the retaining ball 32 may be regulated.

It Will be noted that the relative positions of trigger 21 and lock 28 are such that the trigger portion 25 will lie in the path of lock 28 to. permit a Wed'ging contact between the lock and trigger to prevent undue vibration of the trigger When loclr 28 is in its upper locking position. For this purpose the lock is gouged on its upper rear 'face as at 40 to lie astride the contiguous portion of the trigger and to permit a more compact A assembly of the trigger and lock elements.

In operation, assuming: the hammer` to be in the locked condition shown in Figs. 1 andv 2, the hammer is made ready for use by shifting the lock 28 downwardly and forcing retaining barlll 32 out of thev lower pocket 31 in the side of the lock against the pressure of spring 33 of the lock retaining mechanism until: the upper pocket 31 registers vvithv ballE 32 when the ball, urged by spring 33 Will' enter that pocket and hold lock 28 in its lowered position and out of the path of the trigger toe portion 25, leaving the trigger 21 open for manipulation by the operator, as will be understood.

With lock 28y out of theY path of its. movement, toe piece 25 of the trigger will be free toE move laterally to permit the trigger 21 to rock on pivot 22 and enter slot 20. This movement of the trigger will cause the rearwardly projecting heel portion 24 to bear upon throttle valve 12 against the pressure of spring 1:4 and cause said valve to open. air ports 16 and 17'vvhereupon communication between the piston cylinder 11 and nozzle 18 leading to the air line vvill be established. Conversely, When it is desired to loclrthe trigger the lock 28 is moved upwardly to force retaining ball 82 out of Lipper pocket 81 in the lock against the pressure of the spring 33 until the lower pocket 31 registers with retainingl ball 32 which; will enter said pocket, after which the lock Will; be held with its-gouged portion Ll0. overlapping toe portion 25 of the trigger to effectually prevent rocking of the trigger upon its pivot. Thereafter, the trigger Will; be locked to oppose anyv force applied to it by virtue ot the contact of toe piece 25 of the trigger With lock piece 28 which is of ample size and strength to resist lateral movement of said toe portion 25.

lt will be noted that there has been provided a positive loclr for air hammers and the like which is of Vsimple and economical construction easily applied to existing equipment Without interferring With the efficient operation thereof, and effective when in the locked position to prevent the accidental discharge of the hammer tool Vat such times when the hammer is lying on. the floor in position to be bandied about by persons moving near the hammer or when the ham-- mer is passed from one operator to another, or dropped. Y l/Vhat l claim is:

l. The combination with the trigger and throttle'valve mechanism of an air hammer, of a manually operable trigger lock slidably mounted upon the hammer and adapted for movement substantially parallel to said valve mechanism, andresilient stop mechanism` operable by the locl'; to-l yieldingly retain said lock in released or locking relation to said trigger'.

2. yThe combination With the trigger and throttle valve mechanism of an air hammer, ot a handle enclosing said mechanism and provided with an undercut slotted portion, a lock piece adapted for slidable movement in said. slot toward and avvay from said trigger, andrresilient lock stop mechanism housed in. said slotV and actuated by said lock piece.

3. A safety lock for the triggers of air hammers and the like,` comprising in combination with the handle and the trigger and throttle valve mechanism thereof, of a lock piece slidably mounted in said handle and adapted for engagement with said trigger, and resilient lock stop mechanism operable by said lock piece to retain said lock in locked or released position of the trigger.

In witness Whereof- I have hereto set my hand this 19th day of Gctober, 1925. 

